This invention is directed to article handling and molding systems, and more particularly, to a system for handling and overmolding preform inserts for forming multi-layered preforms.
For molding systems, various processing steps are typically necessary to place an article to be further molded into proper position for such molding. This is particularly true in overmolding processes where one article having already been molded or finished in earlier processes is enlarged or altered through an additional molding process. In many systems, the article to be further processed, for example, through overmolding, is not subject to all handling and processing procedures by one comprehensive machine. Processing steps which may comprise such systems include aligning and orienting the articles, moving the articles to the molding machine, molding or overmolding the articles and removing the articles from the machine for subsequent packaging or further processing. The prior art includes systems or machines directed to these processing steps but fails to disclose a comprehensive machine for systematically performing all of the processed steps.
Article aligning and distributing devices are shown in U.S. Pat. No. 3,827,856 to Van de Walker et al. and U.S. Pat. No. 4,832,176 to Okuma et al. These patents show two different techniques for aligning and handling articles.
Van de Walker et al. discloses an apparatus for loading inserts onto insert receiving seats of a mold. The apparatus is directed for use in mass manufacturing of elongated hollow plastic objects, having inserts at the ends thereof, such as ballpoint pens. The inserts are automatically loaded by vibrating the same into pockets and then lifting them out of the pockets into suction tubes which pass to a horizontal transfer plate and into nests in a vertical transfer plate. A vacuum is employed to maintain the inserts in the nests during movement of the vertical transfer plate to a position adjacent the distal ends of hollow core pins through which air is sucked. The vacuum in the vertical transfer plate is then converted to pressure to cause the inserts to fly across the air gaps of the core pin ends, following which the inserts are maintained on such ends by suction. A mold is enclosed to cause the inserts to engage spring bias plungers, and then plastic is injected.
Okuma et al. discloses a system for automatically distributing and supplying parts. The system includes a base displaceable with respect to a foundation and first and second positioning members fixed to the base at different heights. A movable body is mounted on the base and movable toward and away from a parts installing device by an actuator. A parts feed mechanism is provided which has an angularly movable arm and is mounted on the movable body. A holder is mounted on the arm such that the movable body is displaced by the actuator toward the parts installing device. This allows the holder to supply the parts to the parts installing device after the parts delivered from the parts distributing device to the first positioning member have been delivered through flexible tubular members to the second positioning member. The parts are positioned and held in the holder and the holder is brought into confronting relation to the parts installing device in the parts discharge position.
Accordingly, these patents show only parts handling and aligning systems and not a comprehensive all purpose system for forming multi-layered preforms.
Another step in forming preforms is molding or overmolding. U.S. Pat. No. 4,067,944 to Valyi is directed to overmolding systems. The patent to Valyi discloses a method for obtaining a multi-layered, hollow plastic article having side walls which are oriented in the axial, radial and tangential directions. Plastic material is injection molding about an insert covered core to form a multi-layered parison which is then transferred on the core to first and second blow molds for blow molding to a hollow article. A parison mold and core are maintained in axial alignment in the insert and blow molds are moved therebetween for engagement with the core. In the Valyi case, all transfer takes place for movement of the insert from injection molding to blow molding and accordingly, is not directed to the handling and orientation of the insert prior to molding.
The unloading or transfer of articles to be molded is another step found in molding processes. Particularly, the article is moved from a first position to a second position where at the second position, the article can be oriented for the molding operation.
U.S. Pat. No. Re. 33,237 to Delfer, III discloses an apparatus for producing hollow plastic articles. The apparatus includes an injection molding machine having a first mold portion with at least one cavity therein and a second mold portion having at least one elongated core, which core is adapted to seat in the cavity in the mold closed position. Accordingly, in the mold closed position, a first number of hot hollow plastic articles and an injection molding cycle is formed. A means for reciprocating is provided for reciprocating the mold portions from the mold closed position to a mold open position for forming a gap between the mold portions. A carrier plate means is also provided having at least two sets of cavities therein for cooling the hollow plastic articles. The number of cavities in the carrier plate corresponds to a multiple of at least two times the number of hollow plastic articles produced in an injection molding cycle. A means for moving is also provided for moving the carrier plate means into and out of the gap. In addition, a means for aligning, one set at a time, the carrier plate means cavities to juxtapose the set of cavities with the hollow plastic articles formed in an injection molding cycle, is provided. Finally, a means for transferring the hollow plastic articles to the juxtaposed cavities is also provided.
Yet another step that is used in the molding system processes, is that of sensing the positions of the articles to be molded or overmolded so as to verify their positions and presence. The following systems are directed to position sensing.
U.S. Pat. No. 3,677,680 to Etherington discloses a fluidic sensing device for molding systems. The system disclosed employs fluidic sensing and fluidic control logic to provide alarm signals that prevent loading of molding compound into the mold cavity when the insert in one or more of a group of mold cavities is not properly seated. The system also prevents closing of the mold and insertion of an insert bearing mandrel when all inserts of a previous operation have not been withdrawn from the cavities. A vacuum drawn on the hollow mandrels retains the insert in place upon the end of the mandrel, cools the mandrels, and cooperates with the fluid sensing devices to indicate the presence or absence of the inserts.
An article dated July, 1988 in the publication Plastics World, discloses a system using a closed circuit television camera for visually inspecting mold cavities. The system detects changes from light to dark and alarms the machine if a dark object remains after ejection, signifying a part has remained stuck in the cavity.
U.S. Pat. No. 5,286,426 discloses a method for assembling a lead frame between a pair of molding cavity plates. This method uses light detection means for determining the correct positioning of an inserted part in a molding operation.
While each of these references show sensing systems, neither disclose a comprehensive sensing system for use with a comprehensive insert handling and overmolding system.
There exists, therefore, a need for a comprehensive system for use in conjunction with an injection molding machine for properly unscrambling, handling, moving and overmolding articles, while sensing the absence and presence of the articles throughout movement through the system.